【Leetcode】Implement strStr()

Implement strStr().

Returns the index of the first occurrence of needle in haystack, or -1 if needle is not part of haystack.

比较简单 直接上代码

public class ImplementstrStr {public static void main(String args[]){ImplementstrStr is = new ImplementstrStr();String h = "aaa";String n = "a";System.out.print(is.strStr(h, n));}public int strStr(String haystack, String needle) {   if(haystack==null&&needle==null || haystack.length()==0&&needle.length()==0)    return 0;       if(haystack!=null&&needle.length()==0)  return 0;   if(needle==null||needle.length()==0||haystack==null||haystack.length()==0)return -1;       if(!haystack.contains(needle))return -1;       if(haystack.equals(needle))  return 0;       for(int i=0;i<haystack.length();i++){       if(haystack.charAt(i)==needle.charAt(0) )       if(match((String) haystack.subSequence(i, haystack.length()),needle))       return i;       }return -1;    }private boolean match(String par, String need){//System.out.println(par+"\n"+need);for(int j=0;j<need.length();j++){if(par.charAt(j)!=need.charAt(j))return false;}return true;}}